/*
 * Syncany, www.syncany.org
 * Copyright (C) 2011-2015 Philipp C. Heckel <philipp.heckel@gmail.com> 
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.syncany.operations.down;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.syncany.config.Config;
import org.syncany.database.ChunkEntry.ChunkChecksum;
import org.syncany.database.FileContent;
import org.syncany.database.FileVersion;
import org.syncany.database.MemoryDatabase;
import org.syncany.database.MultiChunkEntry.MultiChunkId;
import org.syncany.database.PartialFileHistory;
import org.syncany.database.SqlDatabase;
import org.syncany.operations.Downloader;
import org.syncany.operations.Operation;
import org.syncany.operations.OperationResult;
import org.syncany.operations.down.actions.FileCreatingFileSystemAction;
import org.syncany.operations.down.actions.FileSystemAction;
import org.syncany.plugins.transfer.TransferManager;

import com.secbox.overlayutil.SecBoxOverlayUtil;

/**
 * Applies a given winners database to the local directory.
 * 
 * <p>
 * Steps:
 * <ul>
 * <li>Determine whether the local branch needs to be updated (new database
 * versions); if so, determine local {@link FileSystemAction}s</li>
 * <li>Determine, download and decrypt required multi chunks from remote storage
 * from file actions (implemented in
 * {@link #determineMultiChunksToDownload(FileVersion, MemoryDatabase, MemoryDatabase)
 * determineMultiChunksToDownload()}, and
 * {@link #downloadAndDecryptMultiChunks(Set) downloadAndDecryptMultiChunks()})
 * </li>
 * <li>Apply file system actions locally, creating conflict files where
 * necessary if local file does not match the expected file (implemented in
 * {@link #applyFileSystemActions(List) applyFileSystemActions()}</li>
 * </ul>
 * 
 * @author Philipp C. Heckel <philipp.heckel@gmail.com>
 */
public class ApplyChangesOperation extends Operation {
	private static final Logger logger = Logger.getLogger(DownOperation.class.getSimpleName());

	private SqlDatabase localDatabase;
	private Downloader downloader;

	private MemoryDatabase winnersDatabase;
	private DownOperationResult result;

	private boolean cleanupOccurred;
	private List<PartialFileHistory> preDeleteFileHistoriesWithLastVersion;

	public ApplyChangesOperation(Config config, SqlDatabase localDatabase, TransferManager transferManager,
			MemoryDatabase winnersDatabase, DownOperationResult result, boolean cleanupOccurred,
			List<PartialFileHistory> preDeleteFileHistoriesWithLastVersion) {

		super(config);

		this.localDatabase = localDatabase;
		this.downloader = new Downloader(config, transferManager);
		this.winnersDatabase = winnersDatabase;
		this.result = result;
		this.cleanupOccurred = cleanupOccurred;
		this.preDeleteFileHistoriesWithLastVersion = preDeleteFileHistoriesWithLastVersion;
	}

	@Override
	public OperationResult execute() throws Exception {
		logger.log(Level.INFO, "Determine file system actions ...");

		FileSystemActionReconciliator actionReconciliator = new FileSystemActionReconciliator(config,
				result.getChangeSet());
		List<FileSystemAction> actions;

		if (cleanupOccurred) {
			actions = actionReconciliator.determineFileSystemActions(winnersDatabase, true,
					preDeleteFileHistoriesWithLastVersion);
		} else {
			actions = actionReconciliator.determineFileSystemActions(winnersDatabase);
		}

		Set<MultiChunkId> unknownMultiChunks = determineRequiredMultiChunks(actions, winnersDatabase);

		downloader.downloadAndDecryptMultiChunks(unknownMultiChunks);
		result.getDownloadedMultiChunks().addAll(unknownMultiChunks);

		applyFileSystemActions(actions);

		return null;
	}

	/**
	 * Finds the multichunks that need to be downloaded to apply the given file
	 * system actions. The method looks at all
	 * {@link FileCreatingFileSystemAction}s and returns their multichunks.
	 */
	private Set<MultiChunkId> determineRequiredMultiChunks(List<FileSystemAction> actions,
			MemoryDatabase winnersDatabase) {
		Set<MultiChunkId> multiChunksToDownload = new HashSet<MultiChunkId>();

		for (FileSystemAction action : actions) {
			if (action instanceof FileCreatingFileSystemAction) { // TODO [low]
																	// This adds
																	// ALL
																	// multichunks
																	// even
																	// though
																	// some
																	// might be
																	// available
																	// locally
				multiChunksToDownload.addAll(determineMultiChunksToDownload(action.getFile2(), winnersDatabase));
			}
		}

		return multiChunksToDownload;
	}

	/**
	 * Finds the multichunks that need to be downloaded for the given file
	 * version -- using the local database and given winners database. Returns a
	 * set of multichunk identifiers.
	 */
	private Collection<MultiChunkId> determineMultiChunksToDownload(FileVersion fileVersion,
			MemoryDatabase winnersDatabase) {
		Set<MultiChunkId> multiChunksToDownload = new HashSet<MultiChunkId>();

		// First: Check if we know this file locally!
		List<MultiChunkId> multiChunkIds = localDatabase.getMultiChunkIds(fileVersion.getChecksum());

		if (multiChunkIds.size() > 0) {
			multiChunksToDownload.addAll(multiChunkIds);
		} else {
			// Second: We don't know it locally; must be from the winners
			// database
			FileContent winningFileContent = winnersDatabase.getContent(fileVersion.getChecksum());
			boolean winningFileHasContent = winningFileContent != null;

			if (winningFileHasContent) { // File can be empty!
				List<ChunkChecksum> fileChunks = winningFileContent.getChunks();

				// TODO [medium] Instead of just looking for multichunks to
				// download here, we should look for chunks in local files as
				// well
				// and return the chunk positions in the local files
				// ChunkPosition (chunk123 at file12, offset 200, size 250)

				Map<ChunkChecksum, MultiChunkId> checksumsWithMultiChunkIds = localDatabase
						.getMultiChunkIdsByChecksums(fileChunks);

				for (ChunkChecksum chunkChecksum : fileChunks) {
					MultiChunkId multiChunkIdForChunk = checksumsWithMultiChunkIds.get(chunkChecksum);
					if (multiChunkIdForChunk == null) {
						multiChunkIdForChunk = winnersDatabase.getMultiChunkIdForChunk(chunkChecksum);

						if (multiChunkIdForChunk == null) {
							throw new RuntimeException("Cannot find multichunk for chunk " + chunkChecksum);
						}
					}

					if (!multiChunksToDownload.contains(multiChunkIdForChunk)) {
						logger.log(Level.INFO,
								"  + Adding multichunk " + multiChunkIdForChunk + " to download list ...");
						multiChunksToDownload.add(multiChunkIdForChunk);
					}
				}
			}
		}

		return multiChunksToDownload;
	}

	/**
	 * Applies the given file system actions in a sensible order. To do that,
	 * the given actions are first sorted using the
	 * {@link FileSystemActionComparator} and then executed individually using
	 * {@link FileSystemAction#execute()}.
	 */
	private void applyFileSystemActions(List<FileSystemAction> actions) throws Exception {
		// Sort
		FileSystemActionComparator actionComparator = new FileSystemActionComparator();
		actionComparator.sort(actions);

		logger.log(Level.FINER, "- Applying file system actions (sorted!) ...");

		// Apply
		for (FileSystemAction action : actions) {
			if (logger.isLoggable(Level.FINER)) {
				logger.log(Level.FINER, "   +  {0}", action);
			}

			try {
				// showUpdateIcon(action.getFile2().getPath());
				SecBoxOverlayUtil.showUpdateIcon(config.getLocalDir().getAbsolutePath() + "\\" + action.getFile2().getPath());
			} catch (Exception e) {
				logger.log(Level.WARNING, "show update fileIcon error->" + action + ", " + e.getMessage());
			}

			// Execute the file system action

			// Note that exceptions are not caught here, to prevent
			// apply-failed-delete-on-up situations.

			action.execute();

			try {
				SecBoxOverlayUtil.showSyncIcon(config.getLocalDir().getAbsolutePath() + "\\" + action.getFile2().getPath());
				// showSyncIcon(action.getFile2().getPath());
			} catch (Exception e) {
				logger.log(Level.WARNING, "show syncing fileIcon error->" + action + ", " + e.getMessage());
			}
		}
	}
}
